Automatic safety switch



July 21, 1931.

GETCHELL 12815561 AUTOMATIC SAFETY SWITCH Filed Fb, 14, 195o 4 Sheets-Sheet 1 INVENTnoR BenJamJnE. Getc'lzell,

' July Z1, 1931. B. E. GETCHELI. 1,815,561

AUTOMATIC SAFETY SWITCH Filed Feb. 14, 1930 4 Sheets-Sheet 2 Lig- 3- July-21, 1931. B. E. GETCHELL AUTOMATIC SAFETY SWITCH Filed Feb. 14, 1950 4 Sheets-Sheet 3- l l 1 1 1 v INVENTOR Belg/a 1HE. Ye-tabell,

July 21, 19317 B. E. GETCHELL 1,815,561 AUTOMATIC SAFETY SWITCH Filed Feb. 14, 1930 4 sheets-shea 4 Patented July 21, l 1931 UNITED sTATEs PATENT OFFICE t BENJAMIN E. GETCHEIQL, 0F PLAINVILLE, CONNECTICUT, ASSIGNOR TO THE TRUI- BULL ELECTRIC MANUFACTURING COMPANY, OF PLAINVILLE, CONNECTICUT, dA.

CORPORATION OF CONNECTICUT AUTOMATIC SAFETY swircn Application led lFebruary 14,1930. Serial No. 428,342.

My invention relates' particularly to the class of enclosed electric switches having an external handle for the usual manual operation of the switch under normal circuit conditions and fin-additional automatically operated meansfor releasing and throwing the switch to oif position in the event of an overload in the circuit.

rlhe principal object of my invention is to provide an automaticallyy operated means for a switch ot' the above mentioned type which, in the event of an overload in the circuit, will operate to release and open the switch even though the external handle is 5 deliberately held in the on position and which will further operate to move the handle to the olf position as soon as it is released.

Another object is to provide a normally,

inactive automatic means for releasing and throwing the switch to the off position in the event of'anoverload, and which means will fully open the maincontacts of the switch with a quick-break movement and will also move the operating handle to the '0H position.

Another object is to provide a means which will automatically operate the switch in the event of an overload and which will simultaneously move the external operating' handle and all of the correlated parts to such Aa position that no relatching movements or operations are required or, 1n oother words,

.so that nothing .is required of the operator except the usual on and oit movements of the handle either `in the normal operation of the switch or in resetting the automatic/means. l

Another object is to provide a simple and effective hand-operated switch with reliable non-fuse overload release.

-Another object is to provide anautomatic `switch construction including ,a bi-ln'etallic .switch releasing member which is separate and independent of the circuit to be controlled and which member is effected solely by means of a detachableheater unit.

- Another object is to provide an automatic switch construction which is adapted to cover a range of circuit capacities and the operating point/of which may be varied as desired by the use of detachable heater units of predetermined capacities and without any other changes in the switch construction.

Another object is to provide an automatic switch, the operating point of whichF may be determined by means of pre-calibrated heater units which'may be inserted or removed from the front of the switch base without disturbing any of the switchparts or operating mechanisms. Another object is to provide a switch construction of the character described which is capable of quantity production according to standardized methods and which nevertheless is extremely sensitive and reliable.

Another object is to provide aconstruction in which the principal metal parts may be formed of sheet metal stampings. These parts are also designed to facilitate assem bling and produce a simple but rugged and durable construction.

Another object is to provide a combination -l The switch proper together with the thermostatic devices is assembled as a unit and readily connected with the handle and snap action mechanismby simply mounting them in the proper position on the same support.

. The accompanying drawings show one form of mechanism embodying my invention and show means for carrying out the various objects above set'forth. I wish it understood, however, that I consider many features of the invention of substantial value even thoughv the construction may not attain all of the o jects sought.

Fig. 1 is a front view of a switch embody-` ing my nvention the parts being shown in the off or open\circuit position and the cover,` of the box being open and broken away.

v kFig. 2 is a side view and partial section on the plane of lines 2-2 .of Fig. 1.

Fig. 3 is a sectional view on the plane lof the lines 3 3 of Fig. l.

Fig. 4 is a side View similar to Fig. 2 but with the moving parts in the closed circuit or on position, the insulating base being omitted.

Fig. 5 is a side view similar to Fig. 4 but showing the switch tripped and with the parts in the open circuit position and the latch about to be reset.

Fig. 6 is a side View showing the parts including the throwing spring in the on or closed circuit position. Y

Fig. 7 is a front view showing the lever action.

Fig. 8 is a perspective view showing the handle and snap action mechanism and the supporting bracket.

Fig. 9 is an exploded perspective view showing parts of the operating and latching mechanism.

The preferred form of the invention includes a suitable box or housing 10 having a cover 11. Such structures usually have spring latch members such as 12 for holding the cover closed and to facilitate sealing. the box.

These switches also preferably have a safety interlock between the actuating mechanism and the cover of the box so as to prevent the opening of the box when the current is on and to prevent closing the switch when the boX is open. My present invention may embody such features, including for instance a latch 13. 'i

The switch mechanism proper is preferably carried by a bracket having a back plate 14 and a side plate 15 so constructed that the entire switch mechanism can be readily inserted or removed from the box. form the back plate 14 has a tongue 16 adapted to engage one side of the box while the side plate 15 is detachably secured to the other side of the box for instance by 'means of clamped screws such as 17.

The handle and snap action mechanism are mounted on a hub 18 suitably supported on the side plate l5 and the handle 19 is suitably secured to this hub.

The snap action or quick-break mechanism includes adisc 20 mounted on the hub 18 and having a suitable form of lost motion connection therewith. A push rod 21 has one end secured to the disc 20 and the other end guided in the bracket 22 secured to the side plate 15. A spring 23 is mounted on this rod between the bracket and the head 24 of the rod adjacent the disc 20 so that the spring opposes the closing movement of the switch and also tends to hold the switch in the closed circuit position.

The conducting parts of the switch are all carried by an insulating block or base 25 suit- ]n the present.

ably formed for that purpose. This base in turn is supported by brackets 26 and 27 lwhich are mounted* on the back plate 14and secured in place for instance by screws such as 28. The brackets 26 and 27 may have lugs 29 receiving screws 29 for securing them to the base 25.

In the form shown the switch is arranged for a three-wire system having line terminals 30, 31 and 32 and load terminals 33, 34 and 35 so that there are threeswitch units. Each unit has an upper stationary contact 36 and a lower Contact 37 adapted to be connected ing the carrier bar with projections 43 at its opposite ends and loosely guiding the movement ,of these projections in inclined slots 44 in the side plates 26 and 27 respectively. The movement of this carrier is eifected by a system of levers and links, all of which are preferably stamped from sheet metal.

The lever 45 is provided with pivots 46 which are supported in the. openings such as 46 in the side plates. The arms of the lever 45 are provided with projecting pins 47 and 47 which are loosely connected with the rear ends of links 48 'and 48 respectively, and the front ends of these links are loosely connected with the projections 43 on the opposite ends of the carrier bar so that as the lever 45 is rocked or turned on its pivots 46 the carrier bar and accompanying movable switch members are moved in and out, toward and away, from the stationary contacts of the switch. A spring 49 .is mounted on one end of the shaft portion of the lever 45 and tends to move the lever 45 and the carrier bar to the open circuit position.

A rocker 50 has a shaft 51 supported between the two plates 27 and 52 and substantially coaxial with the handle hub although this need not be accurately positioned with respect to the handle. This rocker 50 is provided with a pin 53 which engages loosely in the notch 54 in the disc 20 so that the rocker is operatively connected with the throwing member, with rod 21 and its spring 23. The rocking movement of member 50 is limited by the shoulders 55 and 56, in the edge of the plate 52.

The rocker 50 has a curved slot 57 eccentric to the shaft 51 so that its outer wall acts as a cam engaging a pin or roller 58 on the {loating lever 59. i This lever 59 is preferably formed of twoparts mounted on opposite sides of the rocker 50 and connected by the pin or roller member 5,8 near the center of the lever. The upper end of the lever 59is connected to the projectionl 47 of the lever 45 which extends through'the slot 60 in plate 27 for this purpose. The lower end of the lever-59 has a pin 61. which coacts with the latch member 62 which is pivotally mounted at 63, onthe'plate 27.

The shaft 64 is pivotally supported in the side plates 26 and 27 and is under tension of the spring 65 tending to rotate the shaft anti-clockwise as viewed in Figs. 2 to 5.O

This shaft 64 has a projection linger 66 which coacts with an arm 67 and a finger 68 of the latch 62.

In thel open circuit position, spring 23 holds the disc 20 in the positiony shown in Fig. 8 at which time the rocker 50 is in the position'of Figs. 1 and 2 and the pin or roller 58o1rthe lever 59 is the closest possible to the shaft51. The spring 49 is now holding the lever 45 in the position shown in Figs. 2 and 3 with the pin 47 in the outer end of the slot 60. The action of the pin 47 under these conditions is to hold the pin-61-of the lower end of the floating lever 59 in the upper end of the slot 70 in the latch 62. This pressure tends to rotate thelatch 62 so as to press the arm -67 against the projection 66 of the shaft 64.

away from the pivot shaft 51. The pin 61 at the lower end of the lever 59 4in this-movement is'also moved rearwardly untilit engages the shoulder 71 of the latch 62' which limits its rearward movement and'now serves as the stationary fulcrum for the lever 59.

,The continued rotation of the handle is checked when the pin 53 engages the shoulder 56, at which time the notch 72 in the rocker 50 receives the pin 58 of the lever 59 vjust as the spring 23k has received its maximum compression so that the spring 23, the

spring 49 and the springs 41 and the friction of the-parts all tend to hold thevswitch in the closed circuit position.

To open the circuit by hand thev handle is` operated in the reverse direction and when it has picked up thelost-motion between the hub 18 Aand the disc 20 and starts to rotate the disc the spring 23 snaps the parts quickly to the open circuit position in spite of any attempt to hold the handle. This yopening movement-is accelerated by allthree of the springs above mentioned.

In order to facilitate construction and assembly, the pla-tes 52 and 27 are connected together by anges 75 provided with lugs which fit into slots 76 (see Fig. 9). Screws 77 pass through lugs 78 on the plate 52 and' screw into the plate 27. The plates 27 and 2 thus form an assembly frame for kthe rocker 50 and Athe latch 62 and the floating lever 59.

In order to open the circuit automatically. ,in a pre-determined overload, I provide thermostatic devices in one or more branches of the switch. One of these is shown in Fig. 3 and in Fig. 9. A heater member 80 has one end connected by` a bus bar 81 to switch contact 37 and the other end connected by a bus bar 82 to the load terminal 33. The base 25 is provided with a passage 83 to accommodate this heater member which is inserted from the front and readily detachable. A thermostatic arm 84 formed, of suitable metals having a differential coefficient of eX- pansion is secured to the rear of the base by a bracket 85 and screw, adjacent the heater member 80. The movable head of the thermostatic arm is provided with a .screw 86 which may be adjusted for any desired point. The head of this screw engages in the fork 87 projecting forwardly from the shaft 464 so that when the arm 84 iswarped suiiciently by temperature rise it will rock the shaft 64 in a clockwise direction as viewed in Fig. 3. thus moving the projections 66 out of the path of' movement of the linger 68 on the latch 62.

This allows the pressure of the pin 61 against the inclined shoulder 71 to rock the latch member 62 out of the path of the pin 61 so that the lower end of the lever 59 is thrown rearwardly by the action of the spring 49, the 1ever45 and the pin 47. If

the handle has not been held, this action of course has moved the pin 58 out of the notch 72 in the slot 57 and thus leaves the spring 23 free to act and throw they disc 20 and the rocker50 back to the open circuit position of the parts with a snap action. If for any reason the handle was being held when the thermostatic .release took place, the switch will trip open under the influence of the springs 49 and 41 and as soon as the handle is released the spring 23 will throw it to the off position. When .the handle is returned to the off position the movement of the pin 61 along the surface 68 will return the latch .62 to the 'osition shown in Fig. 4 and permit the pro-V,

jections 6 6 to again take up its position above the finger 68 so that the switch is againV .open circuit position, a rocker, a floatingl leverhaving meansof connection 4with said rocker, one end of said floating lever being .connected to said iirst mentioned lever, a 5 latch coacting with the opposite end of said Ilfloating lever, a rock shaft coacting with said latch, thermostatically actuating means for moving said rock shaft to release said latch and means for oscilla-ting said rocker including a handle and a snap action spring. l 2. In an electric switch, a rocker having a y.limited oscillating movement, a handle having a lost motion connection with said rocker, a snap action spring, means of connection between said rocker and said spring, ya carrier member, a lever connected to said carrier, a stationary contact, a movable contact carried by said carrier for engagement with the stationary contact, a spring pressing said movable contact towards said car- ,r`ier, a spring coacting with said lever and f "tending to move said carrier and movable contact away from the stationary contact and means of connection between said rocker and said lever.

3. In an electric switch, a movable switch member, a floating lever having one end connected to said switch member, an oscillating latch for the other endof said lever, thermostatically actuated means for releasing said latch, a rocker having va cam slot connection with said floating lever, said cam slot having a notch for holding the parts of the switch in the closed circuit position and manually compressible snap action means coacting with said rocker.

4. In an electric switch, a movable switch member, a floating lever having one end connected to said switch member, a pivoted latch coacting with the other end of said floating lever, a rocker member coacting with said floating lever, said latch having means for coacting with said floating lever to hold the parts of the switch in closed circuit position, and means automatically operable upon a predetermined overload normally holding said latch with its shoulder coacting with said ioating lever when the switch is in closed circuit position, said latch and said floating lever having coacting parts whereby the latch is reset by said floating lever.

` 5. In an electric' switch, a movable switch carrier, an assembly unit including a plate having a guide slot for said carrier, a companion plate connected to the first mentioned plate, a rocker pivotally supported between said plates and having a proJecting pin, one of said plates having stop shoulders for limiting the oscillation of said rocker, a latch member pivotally supported by one of said plates between said plates, a floating lever including members arranged on opposite sides of said rocher, a pin connecting said members and extending through said rocher,

said rocker having a cam. slot coacting there with, one end of said'floating lever having means of connection with said latch and means of connectibn between the opposite l ends of said floating lever and said carrier. 6. In an electric switch, a supporting plate,

a rocker pivotally supported thereby, a latch member pivotally carried by said plate and .having an arm with an inclined shoulder and a finger lspaced apart from said arm, afloating lever having a sliding connection with said latch, a movable switch member adapted to be moved in one direction by said lever and a rock shaft having a projection adapted ger and the arm of said latch.

7. In an electric switch, a plate, a lrocker pivotally supported on one side of said plate,

a lever pivotally supported on the opposite side of said plate and having a lateral eXten-l sion projecting through `said plate, said rocker having a cam slot, a floating lever having a pin guided in said cam slot, one end of said lever being connected to the extension of said l'I5 said rocker, one end of said lever having a pin coacting with the arm and shoulder of to be interposed between the end of said iinlever and a latch pivotally supported by said means whereby said latch may be reset by said` lever.

8. In anelectric switch, a rocker, a handle having a lost motion means of connection with said rocker, a snap action spring coacting with said rocker, a. movable switch member, a lever having one end connected to said switch member and having a cam'like connection with said rocker, a. latch'member serving in one position to act as a fulcrum for said lever and permitting said rocker to close the switch, a stop coacting withsaid latch to hold said latch in position to act as said fulcrum and means actuated on an overload to retract said stop and release said latch.

9. In an electric switch, a stationary contact, a movable contact, spring means for normally keeping said contacts out of enga ement, manual means for moving said mova le contact into andout of engagement with said stationary contact, means including pin and slot connections for holding said contacts in engagement, and a thermostatically controlled latching means for normally holding the switch in closed circuit position and for automatically releasing said contact engagement onoverload conditions and including a detachable heater element, a movable latch finger and a floating lever member for connecting said thermostatically controlled latcliing means and said movable Contact.

B'illldtlifllil' E. GEICIIELL. 

